drm/amdkfd: Add support for user-mode trap handlers

A second-level user mode trap handler can be installed. The CWSR trap
handler jumps to the secondary trap handler conditionally for any
conditions not handled by it. This can be used e.g. for debugging or
catching math exceptions.

When CWSR is disabled, the user mode trap handler is installed as
first level trap handler.

Signed-off-by: Shaoyun.liu <shaoyun.liu@amd.com>
Signed-off-by: Jay Cornwall <Jay.Cornwall@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

drivers/gpu/drm/amd/amdkfd/kfd_chardev.c

@@ -432,6 +432,38 @@ out:
 	return err;
 }
 
+static int kfd_ioctl_set_trap_handler(struct file *filep,
+					struct kfd_process *p, void *data)
+{
+	struct kfd_ioctl_set_trap_handler_args *args = data;
+	struct kfd_dev *dev;
+	int err = 0;
+	struct kfd_process_device *pdd;
+
+	dev = kfd_device_by_id(args->gpu_id);
+	if (dev == NULL)
+		return -EINVAL;
+
+	mutex_lock(&p->mutex);
+
+	pdd = kfd_bind_process_to_device(dev, p);
+	if (IS_ERR(pdd)) {
+		err = -ESRCH;
+		goto out;
+	}
+
+	if (dev->dqm->ops.set_trap_handler(dev->dqm,
+					&pdd->qpd,
+					args->tba_addr,
+					args->tma_addr))
+		err = -EINVAL;
+
+out:
+	mutex_unlock(&p->mutex);
+
+	return err;
+}
+
 static int kfd_ioctl_dbg_register(struct file *filep,
 				struct kfd_process *p, void *data)
 {
@@ -980,7 +1012,10 @@ static const struct amdkfd_ioctl_desc amdkfd_ioctls[] = {
 			kfd_ioctl_set_scratch_backing_va, 0),
 
 	AMDKFD_IOCTL_DEF(AMDKFD_IOC_GET_TILE_CONFIG,
-			kfd_ioctl_get_tile_config, 0)
+			kfd_ioctl_get_tile_config, 0),
+
+	AMDKFD_IOCTL_DEF(AMDKFD_IOC_SET_TRAP_HANDLER,
+			kfd_ioctl_set_trap_handler, 0),
 };
 
 #define AMDKFD_CORE_IOCTL_COUNT	ARRAY_SIZE(amdkfd_ioctls)

drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c

@@ -1116,6 +1116,26 @@ out:
 	return retval;
 }
 
+static int set_trap_handler(struct device_queue_manager *dqm,
+				struct qcm_process_device *qpd,
+				uint64_t tba_addr,
+				uint64_t tma_addr)
+{
+	uint64_t *tma;
+
+	if (dqm->dev->cwsr_enabled) {
+		/* Jump from CWSR trap handler to user trap */
+		tma = (uint64_t *)(qpd->cwsr_kaddr + KFD_CWSR_TMA_OFFSET);
+		tma[0] = tba_addr;
+		tma[1] = tma_addr;
+	} else {
+		qpd->tba_addr = tba_addr;
+		qpd->tma_addr = tma_addr;
+	}
+
+	return 0;
+}
+
 static int process_termination_nocpsch(struct device_queue_manager *dqm,
 		struct qcm_process_device *qpd)
 {
@@ -1247,6 +1267,7 @@ struct device_queue_manager *device_queue_manager_init(struct kfd_dev *dev)
 		dqm->ops.create_kernel_queue = create_kernel_queue_cpsch;
 		dqm->ops.destroy_kernel_queue = destroy_kernel_queue_cpsch;
 		dqm->ops.set_cache_memory_policy = set_cache_memory_policy;
+		dqm->ops.set_trap_handler = set_trap_handler;
 		dqm->ops.process_termination = process_termination_cpsch;
 		break;
 	case KFD_SCHED_POLICY_NO_HWS:
@@ -1262,6 +1283,7 @@ struct device_queue_manager *device_queue_manager_init(struct kfd_dev *dev)
 		dqm->ops.initialize = initialize_nocpsch;
 		dqm->ops.uninitialize = uninitialize;
 		dqm->ops.set_cache_memory_policy = set_cache_memory_policy;
+		dqm->ops.set_trap_handler = set_trap_handler;
 		dqm->ops.process_termination = process_termination_nocpsch;
 		break;
 	default:

drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.h

@@ -123,6 +123,11 @@ struct device_queue_manager_ops {
 					   void __user *alternate_aperture_base,
 					   uint64_t alternate_aperture_size);
 
+	int	(*set_trap_handler)(struct device_queue_manager *dqm,
+				    struct qcm_process_device *qpd,
+				    uint64_t tba_addr,
+				    uint64_t tma_addr);
+
 	int (*process_termination)(struct device_queue_manager *dqm,
 			struct qcm_process_device *qpd);
 };

include/uapi/linux/kfd_ioctl.h

@@ -262,6 +262,13 @@ struct kfd_ioctl_get_tile_config_args {
 	 */
 };
 
+struct kfd_ioctl_set_trap_handler_args {
+	uint64_t tba_addr;		/* to KFD */
+	uint64_t tma_addr;		/* to KFD */
+	uint32_t gpu_id;		/* to KFD */
+	uint32_t pad;
+};
+
 #define AMDKFD_IOCTL_BASE 'K'
 #define AMDKFD_IO(nr)			_IO(AMDKFD_IOCTL_BASE, nr)
 #define AMDKFD_IOR(nr, type)		_IOR(AMDKFD_IOCTL_BASE, nr, type)
@@ -322,7 +329,10 @@ struct kfd_ioctl_get_tile_config_args {
 #define AMDKFD_IOC_GET_TILE_CONFIG                                      \
 		AMDKFD_IOWR(0x12, struct kfd_ioctl_get_tile_config_args)
 
+#define AMDKFD_IOC_SET_TRAP_HANDLER		\
+		AMDKFD_IOW(0x13, struct kfd_ioctl_set_trap_handler_args)
+
 #define AMDKFD_COMMAND_START		0x01
-#define AMDKFD_COMMAND_END		0x13
+#define AMDKFD_COMMAND_END		0x14
 
 #endif